The invention relates generally to an uninterruptable power supply (UPS) and, more particularly, to a vehicle-based UPS and system for controlling operation of the vehicle-based UPS.
Emergency sources of power are known as important devices in various applications and industries for providing a safeguard against power outages. It is recognized that the need for dependable and long-lasting sources of emergency power may increase in the near future as utility grid failures become more prevalent. That is, due to the number and severity of storms (lightning, wind, fallen trees, ice, etc), the overload of the country's aging utility's transmission and distribution components, and the potential threat of terrorism, the likelihood of utility grid failures is increasing.
Various types of devices are known for providing such emergency power. Devices such as a gasoline, diesel, propane, or other fueled version of an auxiliary or emergency generator are typically interfaced via a transfer switch to a subset of electrical circuits in a home to provide emergency power. An additional source of emergency power is an Uninterruptible Power Supply (UPS). An UPS is preferred in some instance to generators, as a UPS maintains a continuous supply of electric power to connected equipment by supplying power from a separate source when utility power is not available, as compared to an auxiliary power supply or a standby generator, which do not provide instant protection from a momentary power interruption as is desired for certain types of equipment. For example, a UPS is typically used to protect computers, telecommunication equipment, medical equipment, or other electrical equipment where an unexpected power disruption could cause serious business disruption or data loss, or pose other significant consequences.
It is recognized, however, that UPS systems have their limitations. A key issue with conventional UPS systems is whether the limited amount of energy that is stored in the UPS's battery is sufficient to operate the a device for an extended period of time. For example, individuals that require the use of portable AC powered medical equipment and health monitors need a backup source of power that can last for the duration of the night (depending on the specific medical equipment required) or in a worst case, for the duration of a utility grid failure. Devices such as constant pressure airway passages (CPAP), oxygen concentrators, portable respirators, and heart monitors, need to be ensured of a proper supply of power in order to ensure patient well-being. As the average age of the population increases, there is also an increasing need for such critical care devices and systems, and thereby an associated need for systems that can provide adequate, extended length powering of those devices during utility grid outages.
Therefore, it would be desirable to design a UPS system that provides extended power for external loads in the event of a utility grid failure. It is further desired that such a UPS system provide a steady power source and be maintained at a desirable state of charge (SOC)